Mine love pretty much any kind of treat lol, but they are definatly partial to the Zuke's brand - I get the Bakes (they're crunchy) in Peanut butter & Blueberry and for little Alice I use the Mini Naturals-Peatnut butter (they're very tiny, so perfect for training and they have a soft chewy texture).
My dogs also go absolutely crazy for freeze dried liver treats (I buy any brand as long as it's 100% liver with no additives).
Alice also loves little pieces of apple, pear and banana when I'm eating one
